Content delivery networks are more and more deployed within operator networks, for example of internet content providers or mobile operators. As a consequence there is a need for interconnecting these local content delivery networks. Such a content delivery network interconnection enables for example that an upstream content delivery network that receives a request for content from a client may redirect this request to a downstream content delivery network, for example to a router of the downstream content delivery network which performs further redirection to a content delivery entity providing the content for a user equipment connected to the downstream content delivery network. Such a content delivery network interconnection may for example be useful in cases where users from a certain country travel to other countries and try to receive content from their home operator. A redirection to an operator in the visited country is preferred since this operator might have caches closer to the user's current location. Therefore, this is providing in general a more stabile content stream when requesting content.
Such a conventional interconnection between two content delivery networks may be realized as follows: For example a content service provider has an agreement with a content delivery network provider A for delivery of its content. Independently content delivery network provider A and content delivery network provider B agree to interconnect their content delivery networks CDN. When a user agent respectively end user requests content from a content service provider content delivery network provider A may consider that a delivery by content delivery network provider B is more suitable, for instance because content delivery network B is a so-called access content delivery network allowing end users to directly attach to it. Since the content delivery network A CDN-A and a content delivery network B CDN-B are interconnected with each other the content delivery network A CDN-A may redirect the request of the end user to content delivery network B CDN-B and the contents is then actually delivered to the end user by the content delivery network B CDN-B.
When an end user requests content the content may be provided by HTTP adaptive streaming, abbreviated with HAS, which is defined as a streaming technology allowing a client/user equipment to adaptively switch between multiple bitrates depending on current network conditions. Since HTTP adaptive streaming is HTTP-based, it is a pull-based mechanism with a client/user equipment actively requesting content segments instead of the content being pushed to the client/user equipment by a server. With regard to content delivery network using HTTP adaptive streaming causes problems: HTTP adaptive streaming uses so-called manifest files. Such a manifest file is a file a client/user equipment retrieves when querying for HTTP adaptive streaming content containing information where individual chunks for each supported bitrate of the HAS content stream can be retrieved. A conventional manifest file may be organized according to the “absolute URL without redirection”-principle in which case for each chunk and bitrate combination an absolute URL to a surrogate server/content delivery entity in the corresponding content delivery network is included in the manifest file. A conventional manifest file may also be organized according to the “absolute URLs with redirection”-principle: For each chunk a link to a content delivery network request router performing a further redirection is then included in the manifest file.
This has some drawbacks in particular in a content delivery network interconnection scenario: If for example the client is provided with a manifest file redirecting each chunk to the request router of the downstream content delivery network this implies a complicated request routing process for each individual chunk of the HAS content stream which increases significantly the load between both content delivery networks.
If for example the manifest file contains links to downstream content delivery network surrogates/content delivery entities this inhibits any flexibility with regard to allocation of a chunk request to content delivery network surrogates/content delivery entities in the downstream content delivery network.